The Calera process for the capture and conversion of CO2 takes its lead from nature. The earth’s atmosphere has had higher concentrations of CO2 in the past and nature dealt with these high levels of CO2 by a mineralization process whereby marine organisms use CO2 to form calcium carbonate structures that deposit on the ocean floor over time. It is estimated that up to 100 million billion tonnes of CO2 is stored in the geological record in the form of calcium carbonate.
CO2 Capture and Use — Inspired by Nature
The special form of calcium carbonate that Calera produces in its process mimics the form of calcium carbonate that marine organisms use to make their shells and other structures. The special form of calcium carbonate is a binder that creates structures with high strength and toughness.
Calcium carbonate exists in nature in different forms or polymorphs. The Calera process results in the production of the vaterite polymorph which is stable when stored in the absence of water. When water and other proprietary additives are added to the vaterite polymorph, a cement reaction occurs in which the vaterite transforms via a dissolution and reprecipitation reaction to form another polymorph of calcium carbonate known as aragonite. This conversion of vaterite to aragonite results in a material with high strength, just as natural systems like nacre (mother of pearl) are also constructed from the aragonite polymorph of calcium carbonate.